ROME, April 24 (Reuters) - Former Italian prime minister Silvio Berlusconi paid large sums of money to the Sicilian Mafia to protect himself and his family from kidnapping in the mid-1970s, Italy's highest appeals court said on Tuesday.

Cosa Nostra's protection "was not free", the court said, adding that the media magnate was a victim of extortion.

"Berlusconi handed over conspicuous sums of money to the Mafia," the supreme Court of Cassation said in a 146-page document explaining its decision last month to quash a trial against Marcello Dell'Utri, a Sicilian who worked for Berlusconi in those years.

In the 1970s, Italian criminal organizations routinely kidnapped wealthy people or their children, often in the wealthy north of the country, and held them for ransom.

The most notorious example was John Paul Getty III, the grandson of oil baron John Paul Getty Senior, who was taken from central Rome and held for 5 months by the Calabrian mob in 1973. Getty's ear was cut off and mailed to an Italian newspaper to push the family into paying a ransom.

Vittorio Mangano, a Sicilian mobster later convicted of murder, lived in Berlusconi's home near Milan in the mid-1970s, allegedly to tend the horses. At the time Berlusconi had two small children with his first wife.

In 2008, Berlusconi said Mangano "behaved perfectly. He lived with us and accompanied my children to school".

Mangano died in 2000 of natural causes.

Palermo prosecutor Paolo Borsellino described Mangano as a kingpin of Cosa Nostra's business interests in northern Italy, in one of the last interviews he gave before being assassinated by a Mafia car bomb in 1992.

Although Berlusconi is mentioned in the court ruling, he was not involved in the case.

The judicial document explains why the high court struck down a conviction against Dell'Utri, who is now a senator for Berlusconi's People of Liberty party.

The court threw out Dell'Utri's conviction by two lower courts for colluding with Cosa Nostra because Palermo magistrates had failed to prove part of the case. A retrial will now be held.

Dell'Utri had been sentenced to seven years in prison.

Berlusconi, undermined by sex and corruption scandals, was forced to resign as prime minister last November and replaced by technocrat Mario Monti after Italy was confronted with the risk of plunging into a Greek-style debt crisis.

He says left-wing magistrates have waged a campaign for decades to drive him from power and subvert democracy.

Berlusconi is currently a defendant in five trials, one over charges of paying for sex with an underage prostitute and the others on fraud and corruption charges.